Processes for converting oxygenates to olefins using aluminosilicate catalysts

ABSTRACT

The present invention relates to processes for forming mixed alcohols containing methanol and ethanol. The mixed alcohol can then be used as a feedstock for an oxygenate to olefin reaction system for conversion thereof to ethylene, propylene, and the like. In addition, the olefins produced by the oxygenate to olefin reaction can then be used as monomers for a polymerization of olefin-containing polymers and/or oligomers.

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of and priority from U.S. Ser. No.60/854,832, filed Oct. 27, 2006. The above application is fullyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to processes for forming mixed alcoholsand processes for forming olefins from mixed alcohols, as well asprocesses for producing polyolefins therefrom. More particularly, thepresent invention relates to processes for forming a mixed alcoholfeedstock containing at least methanol and varying amounts of ethanol.

BACKGROUND OF THE INVENTION

Light olefins, defined herein as ethylene and propylene and optionallybutylene, are important commodity petrochemicals useful in a variety ofprocesses for making plastics and other chemical compounds. Ethylene isused to make various polyethylene plastics, and in making otherchemicals vinyl chloride, ethylene oxide, ethyl benzene and alcohol.Propylene is used to make various polypropylene plastics, and in makingother chemicals such as acrylonitrile and propylene oxide.

The petrochemical industry has known for some time that oxygenates,especially alcohols, are convertible into light olefins. The preferredconversion process is generally referred to as an oxygenate to olefin(OTO) reaction process. Specifically, in an OTO reaction process, anoxygenate contacts a molecular sieve catalyst composition underconditions effective to convert at least a portion of the oxygenate tolight olefins. When methanol is the oxygenate, the process is generallyreferred to as a methanol to olefin (MTO) reaction process. Methanol isa particularly preferred oxygenate for the synthesis of ethylene and/orpropylene.

Methanol is one of the major chemical raw materials, ranking third involume behind ammonia and ethylene. Worldwide demand for methanol as achemical raw material continues to rise especially in view of itsincreasingly important role (along with dimethyl ether) as a source ofolefins such as ethylene and propylene and as an alternative energysource, for example, as a motor fuel additive or in the conversion ofmethanol to gasoline.

Methanol (as well as dimethyl ether) can be produced via the catalyticconversion of a gaseous feedstock comprising hydrogen, carbon monoxideand carbon dioxide. Such a gaseous mixture is commonly referred to assynthesis gas or “syngas”.

Methanol is typically produced from the catalytic reaction of syngas ina methanol synthesis reactor in the presence of a heterogeneouscatalyst. For example in one synthesis process, methanol is producedusing a copper/zinc catalyst in a water-cooled tubular methanol reactor.In methanol production, syngas undergoes three reactions, only two ofwhich are independent. These reactions are:CO+2H₂→CH₃OH  (A)CO₂+3H₂→CH₃OH+H₂O  (B)H₂O+CO⇄H₂+CO₂  (C)

As can be seen from Reactions B and C, CO₂ can participate in methanolsynthesis. Nevertheless, it is desirable to minimize the amount of CO₂in the syngas for several reasons. In the first place, a low CO₂ contentin the syngas results in a more reactive mixture for methanol synthesisprovided the CO₂ content is at least about 2%. Furthermore, less CO₂results in lower consumption of hydrogen and lower production of water.Lower water production is useful in applications where some relativesmall amounts of water can be present in the methanol product such as,for example, in connection with a methanol to olefins (MTO) process.Production of methanol with low water content thus eliminates the needto distill water from the syngas product methanol.

The syngas stoichiometry for methanol synthesis from syngas is generallydescribed by the following relationship known as the “StoichiometricNumber” or S_(N).S_(N)=(H₂CO₂)/(CO+CO₂)  (D)

The value of S_(N) theoretically required for methanol synthesis is 2.0.However, for commercial production of methanol from syngas, it isdesirable that the value for S_(N) range from about 1.95 to 2.15.Dimethyl ether (DME) may also be produced from syngas using chemistrysimilar to that used for methanol synthesis.

For example, U.S. Pat. Nos. 6,444,712 and 6,486,219 both describemethods for producing olefins from methanol, by way of using natural gasto make the methanol. The methods include converting the methanecomponent of the natural gas to synthesis gas (syngas) using a steamreformer and a partial oxidation reformer. The syngas from each reformeris combined and sent to a methanol synthesis reactor. The combinedsyngas stream to the methanol synthesis reactor desirably has a syngasnumber of from about 1.4 to 2.6. The methanol product is then used as afeed in a methanol to olefin production process.

Autothermal reforming (ATR) involves the addition of air or oxygen withrelatively smaller proportions of steam to a hydrocarbon feedstock.Reaction of hydrocarbon with oxygen proceeds according to the followinggeneral reaction schemes:C_(n)H_(m)+(n/2)O₂ ⇄nCO+(m/2)H₂  (E)C_(n)H_(m)+(n+m/4)O₂ ⇄nCO₂+(m/2)H₂O  (F)

When methane is the hydrocarbon undergoing oxidative reforming, thesereactions become:CH₄+½O₂⇄CO+2H₂  (G)CH₄+2O₂⇄CO₂+2H₂O  (H)

Autothermal reforming employs both steam reforming and oxidativereforming of the hydrocarbon feed. The exothermic oxidation of thefeedstock hydrocarbons generates sufficient heat to drive theendothermic steam reforming reaction over the catalyst bed. The ATRprocedure is thus run at relatively high temperatures and pressures witha relatively low steam to carbon ratio. The CO₂ content of the syngasfrom ATR processes, however, is fairly low, as is desirable for methanolsynthesis.

Another known reforming process involves primarily partial oxidation ofa hydrocarbon feed with an oxygen-containing gas. Catalytic partialoxidation reforming procedures are known; for purposes of thisinvention, partial oxidation reforming takes place in the absence of acatalyst. Due to the absence of a catalyst, partial oxidation (POX)reforming can operate at very high temperatures with little or no steamaddition to the feedstock. Higher pressures than are used in ATRoperations can be employed in POX reforming. However, the syngascomposition resulting from POX reforming is generally deficient inhydrogen for methanol synthesis, resulting in S_(N) and H₂:CO numbersbelow 2. On the other hand, the CO₂ content of the resulting syngas isgenerally very low which is below the optimum value for methanolsynthesis.

Much of the methanol made today is made under high purityspecifications. Grade A and grade AA methanol are commonly produced.U.S. Pat. No. 4,592,806 discloses a process for producing the grade AAmethanol. The grade AA methanol has a maximum ethanol content of 10 ppmand is produced using a distillation column.

As the production of methanol continues to increase, and the newcommercial uses of methanol also continue to increase, it would beadvantageous to produce variable quality methanol streams, which haveparticular advantages for specific end uses, and which do not have tomeet the stringent requirements of Grades AA and A methanol. It wouldalso be beneficial to provide various processes for which the methanolstreams would be of particular benefit.

Additionally, in many MTO reaction processes, the largest component ofthe oxygenate feedstock is methanol. However, relatively small amountsof oxygenates and/or higher alcohols, such as ethanol, can also bepresent in the feedstock. Some prior art MTO feedstocks have beentreated to reduce the amounts of oxygenates and higher alcohols, whileother prior art MTO feedstocks have been augmented to increase theirrelative content of higher alcohols and other oxygenates, for a varietyof reasons. As a result, most prior art MTO processes utilize feedstocksthat have undergone multiple processing and/or treatment steps to attaina higher proportion of higher alcohols, with respect to methanol.

In addition, when mixed alcohols are used as feedstocks in OTO reactionprocesses, water and carbon dioxide formation or retention can causeproblems with olefin formation, e.g., reduced conversion efficiency. Theprior art has recognized the benefit of reduction of water content andcarbon dioxide content in OTO feedstock streams, but has taught complexcombinations of process steps, creating increased cost and efficiencyproblems.

Various patent applications have been directed to compositionscomprising catalysts such as SAPOs being used with predominantlymethanol-based feedstocks. If any ethanol is used in these systems, itis at a very low level, presumably to prevent the appearance ofimpurities such as acetaldehyde (e.g., which are formed by selectivedehydrogenation of ethanol in the presence of many OTO catalystcompositions) in the olefin-containing product.

The present invention, as described below, details a never before seencombination of OTO process conditions and product formation, which canattain significant improvements over the prior art, including lowerlevels of impurities such as acetaldehyde.

SUMMARY OF THE INVENTION

One aspect of the invention relates to a process for converting anoxygenate feed to a light olefin product comprising: a) providing theoxygenate feed comprising a majority of methanol and at least about 5 wt% ethanol; b) providing a catalyst composition comprising analuminosilicate catalyst and a basic metal oxide co-catalyst; and c)contacting the oxygenate feed with the catalyst composition underconditions sufficient to convert at least a portion of the oxygenatefeed to a light olefin product.

Another aspect of the invention relates to a process for converting anoxygenate feed to an olefin product comprising: a) providing theoxygenate feed; b) providing a catalyst composition comprising analuminosilicate catalyst and a basic metal oxide co-catalyst; and c)contacting the oxygenate feed with the catalyst composition underconditions sufficient to convert at least a portion of the oxygenatefeed to a light olefin product having (i) a prime olefin ratio of atleast 1.5:1, (ii) a prime olefin selectivity of at least 80%, or (iii)both (i) and (ii).

Another aspect of the invention relates to a process for converting anoxygenate feed to an olefin product comprising: a) providing theoxygenate feed comprising a majority of methanol and at least about 5 wt% ethanol; b) providing a catalyst composition comprising analuminosilicate catalyst; and c) contacting the oxygenate feed with thecatalyst composition under conditions sufficient to convert at least aportion of the oxygenate feed to a light olefin product having analdehyde content of not more than about 3,000 wppm.

When process steps are enumerated by alphanumeric characters herein, itshould be understood that their order in the recited process need not beset by the sequential nature of the list, i.e., sequentialnumbers/letters do not necessarily enumerate sequential steps.

Further, as described herein, it is contemplated that embodiments listedseparately, even in different aspects of the invention described herein,may be combined together with one or more other embodiments, providedthat the embodiments do not have features that are mutually exclusive.

DETAILED DESCRIPTION OF THE INVENTION A. Introduction

An oxygenate feedstock, particularly a mixed alcohol compositioncontaining methanol and ethanol, is a useful feedstock for a variety ofcatalytic processes, particularly oxygenate to olefin (OTO) reactionprocesses, in which a catalyst composition, typically containing aprimary oxide catalyst having at least two of Al, Si, and P (e.g., analuminosilicate molecular sieve, preferably a high-silicaaluminosilicate molecular sieve) and preferably a basic metal oxideco-catalyst, can be used to convert the oxygenate feedstock into a lightolefin product, e.g., containing ethylene and/or propylene, preferablyincluding ethylene. The olefins can then recovered and used for furtherprocessing, e.g., in the manufacture of polyolefins such as polyethyleneand/or polypropylene, olefin oligomers, olefin copolymers, mixturesthereof, and/or blends thereof.

In one embodiment, a process for converting an oxygenate feed to a lightolefin product comprises: a) providing an oxygenate feed comprising amajority of methanol and at least about 5 wt % ethanol; b) providing acatalyst composition comprising an aluminosilicate catalyst and a basicmetal oxide co-catalyst; and c) contacting the oxygenate feed with thecatalyst composition under conditions sufficient to convert at least aportion of the oxygenate feed to a light olefin product.

In another embodiment, a process for converting an oxygenate feed to anolefin product comprises: a) providing an oxygenate feed; b) providing acatalyst composition comprising an aluminosilicate catalyst and a basicmetal oxide co-catalyst; and c) contacting the oxygenate feed with thecatalyst composition under conditions sufficient to convert at least aportion of the oxygenate feed to a light olefin product having (i) aprime olefin ratio of at least 1.5:1, (ii) a prime olefin selectivity ofat least 80%, or (iii) both (i) and (ii).

In another embodiment, a process for converting an oxygenate feed to anolefin product comprises: a) providing an oxygenate feed comprising amajority of methanol and at least about 5 wt % ethanol; b) providing acatalyst composition comprising an aluminosilicate catalyst; and c)contacting the oxygenate feed with the catalyst composition underconditions sufficient to convert at least a portion of the oxygenatefeed to a light olefin product having an aldehyde content of not morethan about 3,000 wppm.

B. Methanol and Mixed Alcohol Synthesis Systems

There are numerous technologies available for producing methanolincluding fermentation or the reaction of synthesis gas (syngas) derivedfrom a hydrocarbon feed stream, which may include natural gas, petroleumliquids, carbonaceous materials including coal, recycled plastics,municipal waste, or any other organic material.

The hydrocarbon feed stream that is used in the conversion ofhydrocarbon to syngas is optionally treated to remove impurities thatcan cause problems in further processing of the hydrocarbon feed stream.These impurities can poison many conventional propylene and ethyleneforming catalysts. A majority of the impurities that may be present canbe removed in any conventional manner. The hydrocarbon feed ispreferably purified to remove sulfur compounds, nitrogen compounds,particulate matter, other condensables, and/or other potential catalystpoisons prior to being converted into syngas.

As mentioned above, the hydrocarbon feed stream may be supplied and/orpurified by any conventional means of syngas production, including, forexample, autothermal reforming, partial oxidation, steam or CO₂reforming, or a combination of these chemistries. Methanol and mixedalcohol feedstock compositions and processes for forming same aredisclosed, for example, in commonly-owned, co-pending U.S. ProvisionalApplication No. 60/798,383, filed May 8, 2006 and entitled “Process forthe Production of Mixed Alcohols”, the disclosure of which is fullyincorporated herein by reference.

C. Oxygenate-to-Olefin Conversion Process

1. General Process Description

In one embodiment, the mixed alcohol product composition obtainedaccording to this invention comprises at least a portion of an oxygenatefeedstock that is converted to olefin(s) via contact with an olefinforming catalyst to form the olefin product. The olefin product can thenbe recovered, and water, which generally forms during the conversion ofthe oxygenate(s) in the mixed alcohol composition to olefins, canadvantageously be removed. After removing the water, the olefins can beseparated into individual olefin streams, with each individual olefinstream being available for further processing, if desired.

Although the present application specifically describes combining amethanol/ethanol synthesis system with an OTO reaction system, one ormore additional components may be included in the feedstock that isdirected to the OTO reaction system. For example, the feedstock that isdirected to the OTO reaction system optionally contains, in addition tomethanol and ethanol, one or more aliphatic-containing compounds such asalcohols, amines, carbonyl compounds for example aldehydes, ketones andcarboxylic acids, ethers, halides, mercaptans, sulfides, and the like,and mixtures thereof. The aliphatic moiety of the aliphatic-containingcompounds typically contains from 1 to 50 carbon atoms, preferably from1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, mostpreferably from 1 to 4 carbon atoms.

Non-limiting examples of aliphatic-containing compounds include:alcohols such as methanol, ethanol, n-propanol, isopropanol, and thelike, alkyl-mercaptans such as methyl mercaptan and ethyl mercaptan,alkyl-sulfides such as methyl sulfide, alkyl amines such as methylamine, alkyl ethers such as DME, diethyl ether and methyl ethyl ether,alkyl-halides such as methyl chloride and ethyl chloride, alkyl ketonessuch as dimethyl ketone, alkyl-aldehydes such as formaldehyde andacetaldehyde, and various organic acids such as formic acid and aceticacid.

The various feedstocks discussed above are converted primarily into oneor more olefins. The olefins or olefin monomers produced from thefeedstock typically have from 2 to 30 carbon atoms, preferably 2 to 8carbon atoms, more preferably 2 to 6 carbon atoms, still more preferably2 to 4 carbons atoms, and most preferably ethylene and/or propylene.Non-limiting examples of olefin monomer(s) include ethylene, propylene,butene-1, pentene-1,4-methyl-pentene-1, hexene-1, octene-1 and decene-1,preferably ethylene, propylene, butene-1, pentene-1,4-methyl-pentene-1,hexene-1, octene-1 and isomers thereof. Other olefin monomers caninclude, but are not limited to, unsaturated monomers, diolefins having4 to 18 carbon atoms, conjugated or nonconjugated dienes, polyenes,vinyl monomers, and cyclic olefins.

In a preferred embodiment, the feedstock, which contains methanol andethanol, can be converted to olefin(s) having 2 to 6 carbons atoms,preferably 2 to 4 carbon atoms, more preferably at least including lightolefin(s) (i.e., ethylene and/or propylene), in the presence of amolecular sieve catalyst composition. The most preferred process isgenerally referred to as an oxygenates-to-olefins (OTO) reactionprocess. In an OTO process, typically an oxygenated feedstock, mostpreferably a methanol- and ethanol-containing feedstock, is converted inthe presence of a molecular sieve catalyst composition into one or moreolefins, preferably and predominantly including ethylene and/orpropylene.

In one embodiment, the amount of methanol in the feedstock for the OTOreaction can advantageously be at least about 45 wt %, preferably atleast about 50 wt %, for example at least about 60 wt %, at least about70 wt %, at least about 75 wt %, at least about 80 wt %, at least about85 wt %, at least about 90 wt %, or at least about 95 wt %, based on thetotal weight of feedstock and/or the total weight of the oxygenates inthe feedstock (including any diluent contained therein). In oneembodiment, the amount of methanol in the feedstock for the OTO reactioncan preferably be less than about 97 wt %, for example less than about95 wt %, less than about 90 wt %, less than about 85 wt %, less thanabout 80 wt %, less than about 75 wt %, or less than about 70 wt %,based on the total weight of feedstock and/or the total weight of theoxygenates in the feedstock (including any diluent contained therein).

In one embodiment, the amount of ethanol in the feedstock for the OTOreaction can advantageously be at least about 3 wt %, preferably atleast about 5 wt %, for example at least about 8 wt %, at least about 10wt %, at least about 12 wt %, at least about 15 wt %, at least about 17wt %, at least about 20 wt %, or at least about 25 wt %, based on thetotal weight of feedstock and/or the total weight of the oxygenates inthe feedstock (including any diluent contained therein). In oneembodiment, the amount of ethanol in the feedstock for the OTO reactioncan be less than about 55 wt %, preferably less than 50 wt %, forexample less than 45 wt %, less than 40 wt %, less than 35 wt %, lessthan 30 wt %, less than 25 wt %, less than 20 wt %, less than 15 wt %,or less than 10 wt %, based on the total weight of feedstock and/or thetotal weight of the oxygenates in the feedstock (including any diluentcontained therein).

In one embodiment, the amount of liquid feedstock, fed separately orjointly with a vapor feedstock, to a reactor system can be in the rangefrom about 0.1 wt % to about 85 wt %, preferably from about 1 wt % toabout 75 wt %, more preferably from about 5 wt % to about 65 wt %, basedon the total weight of the feedstock (including any diluent containedtherein). The liquid and vapor feedstocks can be of substantially thesame composition, or contain varying proportions of the same ordifferent feedstock components, optionally with the same or differentdiluent.

2. Description of Olefin Forming Catalyst

Any catalyst capable of converting oxygenates to olefins can be used inthis invention. Molecular sieve catalysts are preferred. Examples ofsuch catalysts include zeolite-based, as well as non-zeolite-based,molecular sieves and can be of the large, medium, or small pore type.Molecular sieve materials all have 3-dimensional, four-connectedframework structure of corner-sharing [TO₄] tetrahedra, where T can beany tetrahedrally coordinated cation. These molecular sieves aretypically described in terms of the size of the ring that defines apore, where the size is based on the number of T atoms in the ring.Other framework-type characteristics include the arrangement of ringsthat form a cage, and, when present, the dimension of channels, and thespaces between the cages. See van Bekkum, et al, Introduction to ZeoliteScience and Practice, Second Completely Revised and Expanded Edition,Volume 137, pages 1-67, Elsevier Science, B.V., Amsterdam, Netherlands(2001).

Non-limiting examples of molecular sieves include small pore molecularsieves (e.g., AEI, AFT, APC, ATN, ATT, ATV, AWW, BIK, CAS, CHA, CHI,DAC, DDR, EDI, ERI, GOO, KFI, LEV, LOV, LTA, MON, PAU, PHI, RHO, ROG,THO, and substituted forms thereof), medium pore molecular sieves (e.g.,AFO, AEL, EUO, HEU, FER, MEL, MFI, MTW, MTT, TON, and substituted formsthereof), large pore molecular sieves (e.g., EMT, FAU, and substitutedforms thereof), intergrowths thereof, and combinations thereof. Othermolecular sieves include, but are not limited to, ANA, BEA, CFI, CLO,DON, GIS, LTL, MER, MOR, MWW, SOD, intergrowths thereof, andcombinations thereof. Non-limiting examples of preferred molecularsieves, particularly for converting an oxygenate-containing feedstockinto olefin(s), can include AEL, AFY, AEI, BEA, CHA, EDI, FAU, FER, GIS,LTA, LTL, MER, MFI, MOR, MTT, MWW, TAM, TON, intergrowths thereof, andcombinations thereof. In a preferred embodiment, the molecular sieve hasan AEI topology and/or a CHA topology (i.e., including an AEI/CHAintergrowth), most preferably at least containing a CHA topology.

The small, medium, and large pore molecular sieves have from a 4-ring toa 12-ring or greater framework-type. In a preferred embodiment, thezeolitic molecular sieves have 6-, 8-, 10-, or 12-ring structures and anaverage pore size in the range from about 3 Å to 15 Å. In a morepreferred embodiment, the molecular sieves, preferably aluminosilicatemolecular sieves, have a 6-ring or an 8-ring structure andadvantageously an average pore size less than about 5 Å, such as in therange from 3 Å to about 5 Å, for example from 3 Å to about 4.5 Å or from3.5 Å to about 4.2 Å.

Other non-limiting examples of zeolitic and non-zeolitic molecularsieves include one or a combination of the following: Beta (U.S. Pat.No. 3,308,069), ZSM-5 (U.S. Pat. Nos. 3,702,886, 4,797,267 and5,783,321), ZSM-11 (U.S. Pat. No. 3,709,979), ZSM-12 (U.S. Pat. No.3,832,449), ZSM-12 and ZSM-38 (U.S. Pat. No. 3,948,758), ZSM-20, ZSM-22(U.S. Pat. No. 5,336,478), ZSM-23 (U.S. Pat. No. 4,076,842), ZSM-34(U.S. Pat. No. 4,086,186), ZSM-35 (U.S. Pat. No. 4,016,245), ZSM-38,ZSM-48 (U.S. Pat. No. 4,397,827), ZSM-50, ZSM-58 (U.S. Pat. No.4,698,217), MCM-1 (U.S. Pat. No. 4,639,358), MCM-2 (U.S. Pat. No.4,673,559), MCM-3 (U.S. Pat. No. 4,632,811), MCM-4 (U.S. Pat. No.4,664,897), MCM-5 (U.S. Pat. No. 4,639,357), MCM-9 (U.S. Pat. No.4,880,611), MCM-10 (U.S. Pat. No. 4,623,527), MCM-14 (U.S. Pat. No.4,619,818), MCM-22 (U.S. Pat. No. 4,954,325), MCM-41 (U.S. Pat. No.5,098,684), M-41S (U.S. Pat. No. 5,102,643), MCM-48 (U.S. Pat. No.5,198,203), MCM-49 (U.S. Pat. No. 5,236,575), MCM-56 (U.S. Pat. No.5,362,697), ALPO-11 (U.S. Pat. No. 4,310,440), ultrastable Y zeolite(USY), mordenite, SSZ-13, titanium aluminosilicates (TASOs) such asTASO-45 (European Patent No. EP-A-0 229 295), boron silicates (U.S. Pat.No. 4,254,297), titanium aluminophosphates (TAPOs) (U.S. Pat. No.4,500,651), mixtures of ZSM-5 and ZSM-11 (U.S. Pat. No. 4,229,424),ECR-18 (U.S. Pat. No. 5,278,345), SAPO-34 bound ALPO-5 (U.S. Pat. No.5,972,203), those disclosed in International Publication No. WO 98/57743published Dec. 23, 1988 (molecular sieve and Fischer-Tropsch), thosedisclosed in U.S. Pat. No. 6,300,535 (MFI-bound zeolites), mesoporousmolecular sieves (U.S. Pat. Nos. 6,284,696, 5,098,684, 5,102,643 and5,108,725), and the like, and intergrowths and/or combinations thereof.The entire disclosure of each of the references in this paragraph ishereby fully incorporated by reference herein.

In a preferred embodiment, the molecular sieve catalyst compositioncomprises an aluminosilicate catalyst composition, preferably arelatively high-silica aluminosilicate catalyst composition. Relativelyhigh-silica aluminosilicates, as used herein, can advantageously includethose having a molar relationship of X₂O₃:(n)YO₂ (wherein X is atrivalent element and Y is a tetravalent element), in which n is atleast about 80, preferably at least about 100, for example at leastabout 120, at least about 150, at least about 180, or at least about200, and typically not more than about 5000, preferably not more thanabout 4000, for example not more than about 3500, not more than about3000, not more than about 2500, or not more than about 2000.Alternatively, n for relatively high-silica aluminosilicates can be fromabout 300 to about 4000, for example from about 300 to about 2500.

Non-limiting examples of trivalent X can include aluminum, boron, iron,indium, gallium, and combinations thereof, preferably at least includingaluminum. Non-limiting examples of tetravalent Y can include silicon,tin, titanium, germanium, and combinations thereof, preferably at leastcontaining silicon.

In embodiments where X represents aluminum and Y represents silicon, thefactor n represents a silica:alumina ratio, also termed Si:Al₂. Anothermeasure of relative proportion in such cases is the ratio of Y:X, or thesilicon:aluminum ratio. In one embodiment, the silicon:aluminum (Si:Al)ratio of relatively high-silica aluminosilicates is at least about 40,preferably at least about 50, for example at least about 60, at leastabout 75, at least about 90, or at least about 100, and typically notmore than about 2500, preferably not more than about 2000, for examplenot more than about 1750, not more than about 1500, not more than about1250, or not more than about 1000. Alternatively, the Si:Al ratio ofrelatively high-silica aluminosilicates can be from about 150 to about2000, for example from about 150 to about 1250.

Other non-limiting examples of aluminosilicate catalysts andcompositions can be found, for instance, in U.S. Patent ApplicationPublication No. 2003/0176751 and U.S. patent application Ser. Nos.11/017,286 (filed Dec. 20, 2004) and 60/731,846 (filed Oct. 31, 2005),the disclosures of each of which are incorporated by reference herein.

The catalyst (molecular sieve) used in this invention can include atleast in part a chabazite (CHA) framework, an AEI framework, and/or atleast one intergrown phase of a CHA framework and an AEI framework.Intergrown molecular sieve phases can be described as disordered planarintergrowths of molecular sieve frameworks, e.g., as referenced indetail in Catalog of Disordered Zeolite Structures, 2000 Edition,published by the Structure Commission of the International ZeoliteAssociation, and in Collection of Simulated XRD Powder Patterns forZeolites, M. M. J. Treacy and J. B. Higgins, 2001 Edition, published onbehalf of the Structure Commission of the International ZeoliteAssociation.

Regular crystalline solids are built from structurally invariantbuilding units, called Periodic Building Units, and are periodicallyordered in three dimensions. Structurally disordered structures showperiodic ordering in dimensions less than three, i.e. in two, one orzero dimensions. This phenomenon is called stacking disorder ofstructurally invariant Periodic Building Units. Crystal structures builtfrom Periodic Building Units are called end-member structures ifperiodic ordering is achieved in all three dimensions. Disorderedstructures are those where the stacking sequence of the PeriodicBuilding Units deviates from periodic ordering up to statisticalstacking sequences.

Analysis of intergrown molecular sieves, such as AEI/CHA intergrowths,can be effected by X-ray diffraction and in particular by comparing theobserved patterns with calculated patterns generated using algorithms tosimulate the effects of stacking disorder. DIFFaX is a computer programbased on a mathematical model for calculating intensities from crystalscontaining planar faults (see M. M. J. Tracey et al., Proceedings of theRoyal Chemical Society, London, A[1991], Vol. 433, pp. 499-520). DIFFaXis the simulation program selected by and available from theInternational Zeolite Association to simulate the XRD powder patternsfor randomly intergrown phases of zeolites (see Collection of SimulatedXRD Powder Patterns for Zeolites, by M. M. J. Treacy and J. B. Higgins,2001, Fourth Edition, published on behalf of the Structure Commission ofthe International Zeolite Association). It has also been used totheoretically study intergrown phases of AEI, CHA, and KFI, as reportedby K. P. Lillerud et al. in Studies in Surface Science and Catalysis,1994, Vol. 84, pp. 543-550.

Where the crystalline (catalyst) material of the invention comprises amixture of CHA and AEI or an intergrowth of a CHA framework and an AEIframework, the material can possess a widely varying AEI/CHA ratio offrom about 99:1 to about 1:99, such as from about 98:2 to about 2:98,for example from about 95:5 to about 5:95. In one embodiment, where thematerial is to be used a catalyst in the conversion of oxygenates toolefins, the intergrowth can preferably be CHA-rich and canadvantageously have a AEI/CHA ratio ranging from about 5:95 to about30:70. In addition, in some cases the intergrown material of theinvention may comprise a plurality of intergrown phases with adistribution of different AEI/CHA ratios. The relative amounts of AEIand CHA framework-types in the intergrowth can be determined by avariety of known techniques, including, but not limited to, transmissionelectron microscopy (TEM) and DIFFaX analysis, using the powder X-raydiffraction pattern of a calcined sample of the catalyst.

The catalyst can be incorporated or mixed with other additive materials.Such an admixture is typically referred to as formulated catalyst or ascatalyst composition. Preferably, the additive materials aresubstantially inert to conversion reactions involving dialkyl ethers(e.g., dimethyl ether) and/or alkanols (e.g., methanol, ethanol, and thelike).

In one embodiment, one or more other materials can be mixed with thecrystalline material, particularly a material that is resistant to thetemperatures and other conditions employed in organic conversionprocesses. Such materials can include catalytically active and inactivematerials and synthetic or naturally occurring zeolites, as well asinorganic materials such as clays, silica, and/or other metal oxidessuch as alumina. The latter may be either naturally occurring or in theform of gelatinous precipitates or gels including mixtures of silica andmetal oxides. Use of a catalytically active material can tend to changethe conversion and/or selectivity of the catalyst in the oxygenateconversion process. Inactive materials suitably can serve as diluents tocontrol the amount of conversion in the process so that products can beobtained in an economic and orderly manner without employing other meansfor controlling the rate of reaction. These materials can beincorporated into naturally occurring clays, e.g., bentonite and kaolin,to improve the crush strength of the catalyst under commercial operatingconditions. The materials (e.g., clays, oxides, etc.) can function asbinders for the catalyst. It can be desirable to provide a catalysthaving good crush strength, because, in commercial use, it can bedesirable to prevent the catalyst from breaking down into powder-likematerials.

Naturally occurring clays that can be employed can include, but are notlimited to, the montmorillonite and kaolin family, which familiesinclude the subbentonites, and the kaolins commonly known as Dixie,McNamee, Georgia and Florida clays, or others in which the main mineralconstituent includes halloysite, kaolinite, dickite, nacrite, oranauxite. Such clays can be used in the raw state as originally mined orinitially subjected to calcination, acid treatment, or chemicalmodification. Other useful binders can include, but are not limited to,inorganic oxides such as silica, titania, beryllia, alumina, andmixtures thereof.

In addition to the foregoing materials, the crystalline material used inthis invention can be composited with a porous matrix material such assilica-alumina, silica-magnesia, silica-zirconia, silica-thoria,silica-beryllia and silica-titania as well as ternary compositions suchas silica-alumina-thoria, silica-alumina-zirconia,silica-alumina-magnesia and silica-magnesia-zirconia.

The relative proportions of crystalline material and inorganic oxidematrix may vary widely. For example, a mixture can include a zeolitecontent ranging from about 1 to about 90 percent by weight and moreusually, particularly when the composite is prepared in the form ofbeads, in the range from about 2 to about 80 weight percent of thecomposite.

Additionally or alternately, non-limiting examples of catalystcomposition components/materials and/or their relative proportions canbe found, e.g., in U.S. Pat. Nos. 5,962,762, 6,004,898, 6,040,264,6,436,869, 6,448,460, and 6,936,566, inter alia, the disclosures of eachof which are fully incorporated herein by reference.

In one embodiment, the catalyst compositions according to the inventioncan (optionally but preferably) additionally contain an active metaloxide co-catalyst. This metal oxide co-catalyst can be present in manyforms and, as follows, in varying degrees of increasing proximity to themolecular sieve catalyst and/or the catalyst composition. For instance,the metal oxide co-catalyst can be present as particulate matterseparate from the formulated catalyst composition particles.Additionally or alternately, the metal oxide co-catalyst can be presentas a component of the formulated catalyst composition particles.Additionally or alternately, the metal oxide co-catalyst can be coatedon the surface and/or in the pores of the molecular sieve catalystitself.

In one embodiment, active metal oxides are those metal oxides, differentfrom typical binders and/or matrix materials, that, when used incombination with a molecular sieve in a catalyst composition, areeffective in extending of the useful life of the catalyst composition.Quantification of the extension in catalyst life is determined by theLifetime Enhancement Index (LEI) as defined by the following equation:

${L\; E\; I} = \frac{\begin{matrix}{{{Lifetime}\mspace{14mu}{of}\mspace{14mu}{Catalyst}\mspace{14mu}{in}\mspace{14mu}{Combination}}\mspace{14mu}} \\{{with}\mspace{14mu}{Active}\mspace{14mu}{Metal}\mspace{14mu}{Oxide}}\end{matrix}}{{Lifetime}\mspace{14mu}{of}\mspace{14mu}{Catalyst}}$where the lifetime of the catalyst or catalyst composition, in the sameprocess under the same conditions, is the cumulative amount of feedstockprocessed per gram of catalyst composition until the conversion offeedstock by the catalyst composition falls below some defined level,for example 10%. An inactive metal oxide will have little to no effecton the lifetime of the catalyst composition, or will shorten thelifetime of the catalyst composition, and will therefore have a LEI lessthan or equal to 1. Thus active metal oxides of the invention are thosemetal oxides, different from typical binders and/or matrix materials,that, when used in combination with a molecular sieve, provide amolecular sieve catalyst composition that has a LEI greater than 1. Bydefinition, a molecular sieve catalyst composition that has not beencombined with an active metal oxide will have a LEI equal to 1.0.

It is found that, by including an active metal oxide in combination witha molecular sieve, a catalyst composition can be produced having an LEIfrom greater than 1 to about 200, for example from about 1.5 to about100. Typically catalyst compositions according to the invention canexhibit LEI values greater than 1.1, for example from about 1.2 to about15, and more particularly greater than 1.3, such as greater than 1.5,such as greater than 1.7, such as greater than 2.

In one embodiment, the active metal oxide when combined with a molecularsieve in a catalyst composition enhances the lifetime of the catalystcomposition in the conversion of a feedstock comprising methanol,preferably into one or more olefin(s).

In one embodiment in which an active metal oxide co-catalyst is present,the metal oxide co-catalyst is a basic metal oxide. One way ofdetermining basicity in metal oxides involves measuring the absorbanceof CO₂ per surface area of metal oxide at a given temperature, e.g.,about 100° C. Without being bound by theory, it is postulated thatabsorbance of CO₂ by the metal oxide indicates the presence of basicsites in the metal oxide and that increasing basicity (or increasing thedensity of basic sites) of metal oxide typically correlates withincreasing CO₂ absorbance. For instance, in some embodiments, the metaloxide co-catalyst can absorb more than 0.03 mg of CO₂ per square meterof metal oxide surface area at about 100° C., for example more than0.035 mg of CO₂ per square meter of metal oxide surface area at about100° C., more than 0.04 mg of CO₂ per square meter of metal oxidesurface area at about 100° C., more than 0.05 mg of CO₂ per square meterof metal oxide surface area at about 100° C., or more than 0.1 mg of CO₂per square meter of metal oxide surface area at about 100° C.Alternately or additionally, in some embodiments, the metal oxideco-catalyst can absorb less than 15 mg of CO₂ per square meter of metaloxide surface area at about 100° C., for example less than 10 mg of CO₂per square meter of metal oxide surface area at about 100° C., less than7 mg of CO₂ per square meter of metal oxide surface area at about 100°C., less than 5 mg of CO₂ per square meter of metal oxide surface areaat about 100° C., or less than 4 mg of CO₂ per square meter of metaloxide surface area at about 100° C.

In order to determine the carbon dioxide uptake of a metal oxide, thefollowing procedure is adopted. A sample of the metal oxide isdehydrated by heating the sample to about 200° C. to 500° C. in flowingair until a constant weight, the “dry weight”, is obtained. Thetemperature of the sample is then reduced to 100° C. and carbon dioxideis passed over the sample, either continuously or in pulses, again untilconstant weight is obtained. The increase in weight of the sample interms of mg/mg of the sample based on the dry weight of the sample isthe amount of adsorbed carbon dioxide.

In a preferred embodiment, the carbon dioxide adsorption can be measuredusing a Mettler TGA/SDTA 851 thermogravimetric analysis system underambient pressure. Using this apparatus, the metal oxide sample can bedehydrated in flowing air to about 500° C. for one hour. The temperatureof the sample can then be reduced in flowing helium to 100° C. After thesample has equilibrated at the desired adsorption temperature in flowinghelium, the sample can be subjected to 20 separate pulses (about 12seconds/pulse) of a gaseous mixture comprising 10 wt % carbon dioxidewith the remainder being helium. After each pulse of the adsorbing gas,the metal oxide sample can be flushed with flowing helium for 3 minutes.The increase in weight of the sample, in terms of mg/mg adsorbent, basedon the adsorbent weight after treatment at 500° C., typically gives theamount of adsorbed carbon dioxide. The surface area of the sample can bemeasured in accordance with the method of Brunauer, Emmett, and Teller(BET) published as ASTM D 3663 to provide the carbon dioxide uptake interms of mg carbon dioxide/m² of the metal oxide.

In one embodiment, the active metal oxide(s) has (have) a BET surfacearea of greater than 10 m²/g, such as greater than 10 m²/g to about 300m²/g. In another embodiment, the active metal oxide(s) has a BET surfacearea greater than 20 m²/g, such as from 20 m²/g to 250 m²/g. In yetanother embodiment, the active metal oxide(s) has a BET surface areagreater than 25 m²/g, such as from 25 m²/g to about 200 m²/g. In apreferred embodiment, the active metal oxide(s) has a BET surface areagreater than 20 m²/g, such as greater than 25 m²/g, and particularlygreater than 30 m²/g.

The active metal oxide(s) used herein can be prepared using a variety ofmethods. It is preferable that the active metal oxide is made from anactive metal oxide precursor, such as a metal salt, such as a halide,nitrate, sulfate, or acetate. Other suitable sources of the metal oxideinclude compounds that form the metal oxide during calcination, such asoxychlorides and nitrates. In one embodiment, the active metal oxide canbe made from a hydrated metal oxide precursor. Hydrated metal oxideprecursors, such as hydrated zirconia, are disclosed, for example, inU.S. Pat. No. 6,844,291, which is incorporated herein by reference inits entirety. According to one method, the active metal oxide isprepared by the thermal decomposition of metal-containing compounds,such as magnesium oxalate and barium oxalate, at high temperatures, suchas 600° C., in flowing air. Thus prepared metal oxides usually have lowBET surface area. In another method, the active metal oxide is preparedby the hydrolysis of metal-containing compounds followed by dehydrationand calcination. In yet another method, the active metal oxide isprepared by the so-called aerogel method (Koper, O. B., Lagadic, I.,Volodin, A. and Klabunde, K. J. Chem. Mater. 1997, 9, 2468-2480). Otheraspects of metal oxides and their preparation can be found, e.g., inU.S. Patent Application Publication No. 2003/0171633 A1 and U.S. Pat.No. 6,995,111, the disclosures of each of which are hereby incorporatedherein by reference in their entirety.

In one embodiment where hydrated metal oxide precursors are utilized,the hydrated metal oxide precursor can be hydrothermally treated underconditions that include a temperature of at least 80° C., preferably atleast 100° C. The hydrothermal treatment typically takes place in asealed vessel at greater than atmospheric pressure. However, a preferredmode of treatment involves the use of an open vessel under refluxconditions. Agitation of hydrated metal oxides in a liquid medium, forexample, by the action of refluxing liquid and/or stirring, can promotethe effective interaction of the hydrated oxide with the liquid medium.The duration of the contact of the hydrated oxide with the liquid mediumcan conveniently be at least 1 hour, such as at least 8 hours. Theliquid medium for this treatment typically has a pH of about 6 orgreater, such as 8 or greater. Non-limiting examples of suitable liquidmedia include water, hydroxide solutions (including hydroxides of NH₄ ⁺,Na⁺, K⁺, Mg²⁺, and Ca²⁺), carbonate and bicarbonate solutions (includingcarbonates and bicarbonates of NH₄ ⁺, Na⁻, K⁺, Mg²⁺, and Ca²⁺), pyridineand its derivatives, and alkyl/hydroxyl amines.

In another embodiment, the active metal oxide is prepared, for example,by subjecting a liquid solution, such as an aqueous solution, comprisinga source of ions of a desired metal to conditions sufficient to causeprecipitation of a hydrated precursor of the solid oxide material, suchas by the addition of a precipitating reagent to the solution.Conveniently, the precipitation can be conducted at a pH above 7. Forexample, the precipitating agent may be a base such as sodium hydroxideor ammonium hydroxide.

Various methods exist for making mixed metal oxide precursors, e.g., wetimpregnation, incipient wetness, and co-precipitation, inter alia.

Non-limiting examples of basic metal oxides include, but are not limitedto, hydrotalcite, oxides of metals in Group 2 of the Periodic Table ofElements, oxides of metals in Group 3 of the Periodic Table of Elements,oxides of metals in Group 4 of the Periodic Table of Elements, a mixedmetal oxide containing one or more metals of Groups 2, 3, and 4 of thePeriodic Table of Elements, or a combination thereof. As used herein,Group 3 metals from the Periodic Table of Elements should be understoodto include Lanthanide series metals and Actinide series metals. In onepreferred embodiment, the metal oxide co-catalyst comprises an oxide ofyttrium. In another preferred embodiment, the metal oxide co-catalystcomprises an oxide of zirconium. In another preferred embodiment, themetal oxide co-catalyst comprises a mixed oxide of yttrium andzirconium. In another preferred embodiment, the metal oxide co-catalystcomprises a mixed oxide of a lanthanide (more preferably, lanthanum) andzirconium. In another preferred embodiment, the metal oxide co-catalystcomprises an oxide of magnesium. In another preferred embodiment, themetal oxide co-catalyst comprises a mixed oxide of a lanthanide (morepreferably, lanthanum) and magnesium.

Naturally occurring hydrotalcite is a mineral found in relatively smallquantities in a limited number of geographical areas, principally, inNorway and in the Ural Mountains. Natural hydrotalcite has a variablecomposition depending on the location of the source. Naturalhydrotalcite is a hydrated magnesium, aluminum and carbonate-containingcomposition, which has been found to have the typical composition,represented as Mg₆Al₂(OH)₁₆CO₃.4H₂O. Natural hydrotalcite deposits aregenerally found intermeshed with spinel and other minerals, such aspenninite and muscovite, from which it is difficult to separate thenatural hydrotalcite.

Synthetically produced hydrotalcite can be made to have the samecomposition as natural hydrotalcite, or, because of flexibility in thesynthesis, it can be made to have a different composition by replacingthe carbonate anion with other anions, such as phosphate ion. Inaddition, the Mg/Al ratio can be varied to control the basic propertiesof the hydrotalcite.

A phosphate-modified synthetic hydrotalcite and a process for itssynthesis are disclosed in U.S. Pat. No. 4,883,533. U.S. Pat. No.3,539,306 discloses a process for preparing hydrotalcite which involvesmixing an aluminum-containing compound with a magnesium-containingcompound in an aqueous medium in the presence of carbonate ion at a pHof at least 8. U.S. Pat. No. 4,656,156 discloses a process for producingsynthetic hydrotalcite by heating a magnesium compound to a temperatureof about 500 to 900° C. to form activated magnesia, adding the activatedmagnesia to an aqueous solution containing aluminate, carbonate andhydroxyl ions, and then agitating the resultant mixture at a temperatureof about 80 to 100° C. for 20 to 120 minutes to form a low density, highporosity hydrotalcite. A similar process is disclosed in U.S. Pat. No.4,904,457. The entire disclosure of each of the above references isincorporated herein by reference.

Hydrotalcite compositions containing pillaring organic, inorganic, andmixed organic/inorganic anions are disclosed in U.S. Pat. No. 4,774,212,the entire disclosure of which is incorporated herein by reference. Thecompositions are anionic magnesium aluminum hydrotalcite clays havinglarge inorganic and/or organic anions located interstitially betweenpositively charged layers of metal hydroxides. The compositions are ofthe formula:[Mg_(2x)Al₂(OH)_(4x+4)]Y_(2/n) ^(n−).ZH₂Owhere Y is a large organic anion selected from the group consisting oflauryl sulfate, p-toluenesulfonate, terephthalate,2,5-dihydroxy-1,4-benzenedisulfonate, and 1,5-naphthalenedisulfonate orwhere Y is an anionic polyoxometalate of vanadium, tungsten ormolybdenum. In the above cases, x is from 1.5 to 2.5, n is 1 or 2 and Zis from 0 to 3, except that when Y is polyoxometalate, n is 6.

An aggregated synthetic hydrotalcite having a substantially spheroidalshape and an average spherical diameter of up to about 60 μm, composedof individual platy particles, is disclosed in U.S. Pat. No. 5,364,828,the entire disclosure of which is incorporated herein by reference. Thisform of hydrotalcite is prepared from aqueous solutions of solublemagnesium and aluminum salts, which are mixed in a molar ratio of fromabout 2.5:1 to 4:1, together with a basic solution containing at least atwo-fold excess of carbonate and a sufficient amount of a base tomaintain a pH of the reaction mixture in the range of from about 8.5 toabout 9.5.

Prior to use in the catalyst composition of the invention, it may bedesirable to calcine the hydrotalcite to remove the water inherentlycontained by the material. Suitable calcination conditions include atemperature of from about 300° C. to about 800° C., such as from about400° C. to about 600° C. for about 1 to about 16 hours, such as forabout 3 to about 8 hours.

In one embodiment, in which a basic metal oxide co-catalyst is presentin combination with the molecular sieve catalyst, the weight/weightratio of molecular sieve catalyst (alone, without binder, matrix, etc.)to basic metal oxide co-catalyst can be from about 100:1 to about 1:2,preferably from about 50:1 to about 1:1, for example from about 25:1 toabout 3:2 or from about 10:1 to about 2:1.

3. Adding Other Oxygenates to Mixed Alcohol Compositions

In an optional embodiment of this invention, the mixed alcoholcomposition can be converted into olefin(s) along with other oxygenatesor diluents. The additional oxygenates or diluents can be co-mixed withthe mixed alcohol composition, or can be added as a separate feed streamto an oxygenate conversion reactor in an OTO process. In one embodiment,the additional oxygenate includes one or more alcohols, preferablyaliphatic alcohol(s) where the aliphatic moiety of the alcohol(s) hasfrom 3 to 10 carbon atoms, preferably from 3 to 5 carbon atoms, and mostpreferably from 3 to 4 carbon atoms. The alcohols include lower straightand branched chain aliphatic alcohols and their unsaturatedcounterparts. Non-limiting examples of additional oxygenates includen-propanol, isopropanol, methyl ethyl ether, dimethyl ether, diethylether, diisopropyl ether, methyl propyl ethers, ethyl propyl ethers,methyl butyl ethers such as methyl t-butyl ether, formaldehyde, dimethylcarbonate, dimethyl ketone, acetic acid, and mixtures thereof. In oneembodiment, the feedstock for the OTO process can include, aside frommethanol and ethanol, one or more of a propanol, dimethyl ether, diethylether, methyl t-butyl ether, acetic acid, or a combination thereof.

The mixed alcohol feedstock, in one embodiment, contains one or morediluent(s), typically used to reduce the concentration of alcohol(predominantly methanol), and are generally substantially non-reactivewith the oxygenate(s) in the feedstock and/or with the molecular sievecatalyst composition. Non-limiting examples of diluents include helium,argon, nitrogen, carbon monoxide, carbon dioxide, water, essentiallynon-reactive paraffins (e.g., alkanes such as methane, ethane, propane,and the like), essentially non-reactive aromatic compounds, and mixturesthereof. In one embodiment, the amount of diluent in the feedstock canbe from about 0.1 mol % to about 99 mol %, based on the total number ofmoles of the feedstock and any added diluent, preferably from about 0.5mol % to about 80 mol %, for example from about 1 mol % to about 50 mol% or from about 3 mol % to about 25 mol %.

4. General Conditions for Converting Methanol/Ethanol to Olefins

According to the OTO reaction process of the invention, oxygenates canbe contacted with an olefin forming catalyst to form an olefin product,particularly a light olefin product such as ethylene and/or propylene.The process for converting a feedstock, especially a feedstockcontaining one or more oxygenates, in the presence of an olefin-formingmolecular sieve catalyst composition of the invention, is carried out ina reaction process in a reactor, where the process is a fixed bedprocess, a fluidized bed process (includes a turbulent bed process),preferably a continuous fluidized bed process, and most preferably acontinuous high velocity fluidized bed process.

The OTO reaction processes can take place in a variety of catalyticreactors, for instance, circulating fluidized bed reactors, riserreactors, hybrid reactors that have a dense bed or fixed bed reactionzones and/or fast fluidized bed reaction zones coupled together, and thelike. Suitable conventional reactor types can be found, for example, inU.S. Pat. Nos. 4,076,796 and 6,287,522, and in Fluidization Engineering,D. Kunii and O. Levenspiel, Robert E. Krieger Publishing Company, NewYork, N.Y. (1977), which is herein fully incorporated by reference.

One preferred reactor type is a riser reactor. These types of reactorsare generally described, for example, in Riser Reactor, Fluidization andFluid-Particle Systems, pages 48 to 59, F. A. Zenz and D. F. Othmo,Reinhold Publishing Corporation, New York, 1960, in U.S. Pat. No.6,166,282 (fast-fluidized bed reactor), and in U.S. patent applicationSer. No. 09/564,613 filed May 4, 2000 (multiple riser reactor), whichare all herein fully incorporated by reference.

The conversion temperature employed in the conversion process,specifically within the reactor system, is typically from about 392° F.(200° C.) to about 1832° F. (1000° C.). In one embodiment, the averagereaction temperature employed in the conversion process, specificallywithin the reactor, can be from about 482° F. (250° C.) to about 1472°F. (800° C.), preferably from about 482° F. (250° C.) to about 1382° F.(750° C.), for example from about 572° F. (300° C.) to about 1202° F.(650° C.), from about 662° F. (350° C.) to about 1112° F. (600° C.),from about 662° F. (350° C.) to about 1022° F. (550° C.), or from about752° F. (400° C.) to about 932° F. (500° C.).

The pressure employed in the conversion process, specifically within thereactor, is generally not critical. The reaction pressure can desirablybe based on the partial pressure of the feedstock, exclusive of anydiluent therein. In one embodiment, the reaction pressure employed inthe process ranges from about 0.1 kPaa (kPa absolute) to about 5 MPaa(MPa absolute), preferably from about 5 kPaa to about 1 MPaa, mostpreferably from about 20 kPaa to about 500 kPaa.

The weight hourly space velocity (WHSV), particularly in a process forconverting a feedstock containing one or more oxygenates in the presenceof a molecular sieve catalyst composition within a reaction zone, isdefined as the total weight of the feedstock, excluding any diluents, tothe reaction zone per hour per weight of molecular sieve in themolecular sieve catalyst composition in the reaction zone. The WHSV canadvantageously be maintained at a level sufficient to keep the catalystcomposition in a fluidized state within a reactor.

In one embodiment, the WHSV can range from about 1 hr⁻¹ to about 5000hr⁻¹, preferably from about 2 hr⁻¹ to about 3000 hr⁻¹, more preferablyfrom about 5 hr⁻¹ to about 1500 hr⁻¹, most preferably from about 10 hr⁻¹to about 1000 hr⁻¹. In a preferred embodiment, the WHSV can be greaterthan 20 hr⁻¹. Where a feedstock containing methanol and dimethyl etheris being converted, the WHSV can, in one embodiment, be from about 20hr⁻¹ to about 300 hr⁻¹.

The superficial gas velocity (SGV) of the feedstock including diluentand reaction products within the reactor system can preferably besufficient to fluidize the molecular sieve catalyst composition within areaction zone in the reactor system. In one embodiment, the SGV in theprocess, particularly within the reactor system, more particularlywithin the reaction zone of the riser reactor(s), can be at least 0.1meter per second (m/sec), preferably greater than about 0.5 m/sec, morepreferably greater than about 1 m/sec, even more preferably greater thanabout 2 m/sec, yet even more preferably greater than about 3 m/sec, andmost preferably greater than about 4 m/sec. See, for example, U.S.patent application Ser. No. 09/708,753 filed Nov. 8, 2000, thedisclosure of which is hereby incorporated by reference.

According to one embodiment, the conversion of oxygenate, particularlythe conversion of methanol, to form olefin(s) is from about 90 wt % toabout 99.9 wt %. According to another embodiment, the conversion ofmethanol to olefin(s) is from about 92 wt % to about 99 wt %, typicallyfrom about 94 wt % to about 98 wt %.

According to another embodiment, the conversion of methanol to olefin(s)can be above about 98 wt % to less than about 100 wt %. According toanother embodiment, the conversion of methanol to olefin(s) can be fromabout 98.1 wt % to less than about 100 wt %, or alternately from about98.2 wt % to about 99.8 wt %. According to another embodiment, theconversion of methanol to olefin(s) can be from about 98.2 wt % to lessthan about 99.5 wt %, or alternately from about 98.2 wt % to about 99 wt%.

It can be desirable to maintain an amount of coke on the catalyst in thereaction vessel, e.g., to enhance the formation of desired olefinproduct, particularly ethylene and propylene. For instance, in oneembodiment, it is particularly desirable that the level of coke on thecatalyst in the reactor be at least about 1.5 wt %, preferably fromabout 2 wt % to about 30 wt %.

5. Impact of Ethylene-Propylene Ratio in OTO Reactions

It has been discovered that ethanol has a selectivity for ethylene underOTO and ETO (ethanol-to-olefins) reaction conditions, which approaches100 weight percent. Methanol, in contrast, produces ethylene andpropylene in generally equal amounts under OTO and ETO reactionconditions. By increasing the amount of ethanol contained in an OTOfeedstock, the amount of ethylene produced in the OTO reaction systemrelative to propylene can be correspondingly increased. See, e.g., U.S.Patent Application Publication No. 2005-0107482, which is incorporatedherein by reference in its entirety, for further discussion ofethylene-propylene ratio and its impact on OTO reaction processes, interalia.

6. OTO Reaction Product Properties and Characteristics

The reaction of oxygenate(s) according to the invention, as facilitatedby catalyst compositions according to the invention, inter alia, canadvantageously produce an olefin-containing product according to theinvention. This olefin-containing product can have various quantifiableproperties and characteristics, which can depend on a number of factorsincluding, but not limited to, reaction conditions (e.g., temperatures,pressures, WHSVs, flow rates, etc.), reactor geometry, chemical and/orphysical nature of the catalyst composition, catalyst coking levels,catalyst regeneration conditions, oxygenate conversion, oxygenatecomposition, and the like, and combinations thereof. The aforementionedquantifiable properties and characteristics can include, but are in noway limited to, prime olefin selectivity, prime olefin ratio, impuritycontent (e.g., aldehydes, acids, alkanes, dienes and/or polyenes,alkynes, ketones, aromatic compounds, alkyl ethers, alkanols, unreactedoxygenates, unreacted syngas/natural gas components, catalyst fines, insome cases α-disubstituted olefins such as isobutylene, in some casesheavier olefins such as C₆+ olefins, and the like, and combinationsthereof), and the like.

As used herein, the phrase “prime olefin selectivity” should beunderstood by one of ordinary skill in the art to mean theconversion-weighted average weight of ethylene and propylene produced inthe reaction product divided by the weight of CH₂ groups in theoxygenate feed converted. As used herein, the phrase “prime olefinratio” should be understood by one of ordinary skill in the art to meanthe ratio of the conversion-weighted average yield of ethylene to theconversion-weighted average yield of propylene in the reaction product.

In one embodiment, the prime olefin selectivity (or POS) of the OTOreaction product according to the invention can be greater than 79%,preferably at least 80%, for example from 80% to 95%, from 80% to 90%,or from 80% to 85%, or alternately at least 81%.

In one embodiment, the prime olefin ratio (or POR) of the OTO reactionproduct according to the invention can be greater than 4:3, morepreferably at least 10:7, for example at least 3:2, at least 8:5, atleast 13:8, at least 5:3, at least 7:4, at least 9:5, or at least 11:6.In one embodiment, the prime olefin ratio (or POR) of the OTO reactionproduct according to the invention can be less than 8:3, for example nomore than 21:8, no more than 13:5, no more than 5:2, no more than 17:7,no more than 7:3, no more than 9:4, no more than 11:5, or no more than13:6.

In one embodiment, the amount of aldehyde impurities, particularly theamount of acetaldehyde impurities, in the olefin-containing product canbe less than about 10,000 wppm, preferably not more than about 5,000wppm, for example not more than about 4,000 wppm, not more than about3,000 wppm, not more than about 2,500 wppm, not more than about 2,000wppm, not more than about 1,500 wppm, not more than about 1,000 wppm,not more than about 750 wppm, or not more than about 500 wppm, based onthe total weight of the feedstock (including any diluent containedtherein).

D. Olefin Product Recovery and Use

In one embodiment, olefin product and other gases can be withdrawn fromthe reactor and passed through a recovery system. Any recovery system,technique, and/or sequence useful in separating olefin(s) and purifyingolefin(s) from other gaseous components can be used in this invention.Examples of recovery systems can include, but are not limited to, one ormore or a combination of various separation, fractionation, and/ordistillation towers, columns, splitters, other associated equipment(e.g. various condensers, heat exchangers, refrigeration systems orchill trains, compressors, knock-out drums or pots, pumps, etc.), andthe like, multiples, and combinations thereof.

Non-limiting examples of distillation towers, columns, splitters, ortrains used alone or in combination can include one or more of ademethanizer (preferably a high temperature demethanizer), adeethanizer, a depropanizer (preferably a wet depropanizer), a washtower often referred to as a caustic wash tower and/or quench tower, anabsorber, an adsorber, a membrane, an ethylene (C₂) splitter, apropylene (C₃) splitter, a butene (C₄) splitter, and the like,multiples, and combinations thereof.

Various recovery systems useful for recovering predominately olefin(s),preferably prime or light olefin(s) such as ethylene, propylene, and/orbutane, are described, for example, in U.S. Pat. Nos. 5,960,643;5,019,143; 5,452,581; 5,082,481; 5,672,197; 6,069,288; 5,904,880;5,927,063; 6,121,504; 6,121,503; and 6,293,998; the disclosures of whichare all fully incorporated herein by reference.

Generally, accompanying most recovery systems is the production,generation, and/or accumulation of additional products, by-products,and/or contaminants, along with the preferred products [e.g., primeolefin(s)]. The preferred prime products, i.e., light olefins such asethylene and propylene, are typically purified for use in derivativemanufacturing processes, such as polymerization processes. Therefore, ina preferred embodiment of the recovery system, the recovery system alsoincludes a purification system. For example, the light olefin(s)produced, particularly in a MTO process, can be passed through apurification system that removes low levels of by-products and/orcontaminants.

Non-limiting examples of contaminants and by-products include generallypolar compounds, e.g., water, alcohols, carboxylic acids, ethers, carbonoxides, sulfur compounds (such as hydrogen sulfide, carbonyl sulfides,and mercaptans), ammonia and other nitrogenated compounds, arsine,phosphine, chlorides, and the like, and combinations thereof. Othercontaminants and by-products can include, but are not limited to,hydrogen and hydrocarbons such as acetylene, methyl acetylene,propadiene, butadiene, butyne, and the like, and combinations thereof.

Other recovery systems including purification systems, for example forthe purification of olefin(s), are described in Kirk-Othmer Encyclopediaof Chemical Technology, 4th Edition, Volume 9, John Wiley & Sons, 1996,pages 249-271 and 894-899, which is hereby incorporated by referenceherein. Purification systems are also described in, for example, U.S.Pat. No. 6,271,428, U.S. Pat. No. 6,293,999, and U.S. patent applicationSer. No. 09/689,363 filed Oct. 20, 2000, the disclosures of which arehereby incorporated by reference herein.

E. Oligomerization/Polymerization Of Olefin Product

The ethylene and propylene streams produced and recovered according tothis invention can be polymerized to form oligomeric, polymeric, and/orplastic compositions, e.g., polyolefins, particularly oligomers,homopolymers, copolymers, and/or blends of monomers, such as ethyleneand propylene, formed by a process according to this invention. Anysuitable process for forming polyethylene and/or polypropyleneoligomers, homopolymers, copolymers, and/or blends can be used.Catalytic polymerization processes are typically preferred. Particularlypreferred are metallocene, Ziegler/Natta, aluminum oxide, and acidcatalytic systems. See, for example, U.S. Pat. Nos. 3,258,455;3,305,538; 3,364,190; 5,892,079; 4,659,685; 4,076,698; 3,645,992;4,302,565; and 4,243,691, the catalyst and process descriptions of eachbeing expressly incorporated herein by reference. In general, thesemethods involve contacting the ethylene or propylene product with apolyolefin-forming catalyst at a pressure and temperature effective toform the polyolefin product.

In one embodiment, the ethylene or propylene product can be contactedwith a metallocene catalyst to form an oligoolefin or a polyolefin(hereinafter, collectively “polyolefin”). In some embodiments, thepolyolefin forming process can be carried out at a temperature fromabout 50° C. to about 320° C., and/or at low, medium, or high pressure,being anywhere from below about 1 barg (1.02 kg/cm² gauge) to about 3200barg (3264 kg/cm² gauge). For processes desired to be carried out insolution, an inert diluent can be used. In this type of operation, itcan be desirable that the pressure range from about 10 barg (10.2 kg/cm²gauge) to about 150 barg (1.53 kg/cm² gauge), and preferably at atemperature from about 120° C. to about 250° C. For gas phase processes,it can be desirable that the temperature generally be from about 60° C.to about 120° C., and that the operating pressure range from about 5barg (5.1 kg/cm² gauge) to about 50 barg (51 kg/cm² gauge).

In addition to polyolefins, numerous other olefin derivatives may beformed from the olefin products (e.g., ethylene, propylene, and C₄₊olefins, particularly butylenes) manufactured according to theinvention. The olefins manufactured according to the invention can alsobe used to synthesize such compounds as aldehydes, acids such as C₂-C₁₃mono carboxylic acids, alcohols such as C₂-C₁₂ mono alcohols, estersthat can be made from the C₂-C₁₂ mono carboxylic acids and the C₂-C₁₂mono alcohols, linear alpha-olefins, vinyl acetate, ethylene dichlorideand vinyl chloride, ethylbenzene, ethylene oxide, cumene, acrolein,allyl chloride, propylene oxide, acrylic acid, ethylene-propylenerubbers, acrylonitrile, trimers and dimers of ethylene and propylene,and the like, and blends and copolymers and combinations thereof. TheC₄₊ olefins, butylene in particular, are particularly suited for themanufacture of aldehydes, acids, alcohols, esters that can be made fromC₅-C₁₃ mono carboxylic acids and C₅-C₁₃ mono alcohols, and linearalpha-olefins.

F. Examples

The present invention can be better understood in view of the followingnon-limiting examples, which should not be read in any way to undulylimit the scope of the invention, as defined by the appended claims.

Example 1 OTO Conversion of a Methanol/Ethanol Feed Using SAPO+Yttria

In Example 1, the oxygenates-to-olefins process used a methanol feedwith varying amounts of ethanol over a particulate SAPO molecular sievecatalyst, which is a CHA/AEI intergrowth (EMM-2) and having an Si:Al₂ratio of about 0.1, and separate particles of yttrium oxide as the Group3 metal oxide co-catalyst. The relative proportion of molecular sievecatalyst to metal oxide in Example 1 was about 5:1. The presence ofethanol in the methanol feed can typically lead to elevated levels ofacetaldehyde in the product, e.g., through dehydrogenation of theethanol. Process conditions of about 475° C. reactor temperature andabout 25 psig (0.17 MPag) reactor pressure were used, as well as a WHSVof about 100 hr⁻¹, based on methanol. Prime olefin selectivity and primeolefin ratio results were obtained under these conditions and are shownin Table 1 below, along with the content of acetaldehyde impurity in theresultant product.

TABLE 1 Acetaldehyde % POS [wt %] POR formed [wt %] Ethanol EMM-2 +EMM-2 + EMM-2 + in Feed EMM-2 Y₂O₃ EMM-2 Y₂O₃ EMM-2 Y₂O₃  0 74.7 71.10.88 0.69 0.25 0.02 10 74.6 76.6 1.2 1.0 3.3 0.84 20 74.2 78.2 1.5 1.44.6 1.0

Table 1 indicates that POS did not change much with increasing ethanolcontent in the feedstock where there is no metal oxide co-catalyst.However, the use of a metal oxide co-catalyst in combination with theSAPO catalyst led to a significant increase in POS with increasingethanol feed content.

Table 1 also indicates that POR increased steadily with increasingethanol content in the feedstock, whether the metal oxide co-catalyst ispresent or not. In Example 1, the presence of metal oxide co-catalystyielded reduced POR values compared to those of the SAPO catalyst alone.

Table 1 further indicates that the presence of ethanol in the feedstocksignificantly increases the acetaldehyde content in the product, butformation of this impurity can be significantly controlled throughco-use of the metal oxide co-catalyst.

Example 2 OTO Conversion of a Methanol/Ethanol Feed According to theInvention Using an Aluminosilicate and a Basic Metal Oxide

In Example 2, the oxygenates-to-olefins process used a methanol feedwith varying amounts of ethanol over a particulate aluminosilicatemolecular sieve intergrowth catalyst having an Si:Al ratio of about 100(high-silica) and separate particles of yttrium oxide as the Group 3metal oxide co-catalyst. The relative proportion of molecular sievecatalyst to metal oxide in Example 2 was also about 5:1. As in Example1, the presence of ethanol in the methanol feed can lead to elevatedlevels of acetaldehyde in the product, e.g., through dehydrogenation ofthe ethanol. Process conditions of about 540° C. reactor temperature andabout 25 psig (0.17 MPag) reactor pressure were used, as well as a WHSVof about 100 hr⁻¹, based on methanol. Prime olefin selectivity and primeolefin ratio results were obtained under these conditions and are shownin Table 2 below, along with the content of acetaldehyde impurity in theresultant product.

TABLE 2 POS [wt %] POR Acetaldehyde Hi-Si Hi-Si formed [wt %] % EthanolHi-Si  cat + Hi-Si  cat + Hi-Si Hi-Si in Feed cat Y₂O₃ cat Y₂O₃ catcat + Y₂O₃  0 76.0 73.9 1.2 1.2 0.16 <0.01 10 76.0 80.5 1.5 1.6 3.2 0.0120 77.2 81.3 1.9 1.9 5.1 0.05

Table 2 indicates that the use of a metal oxide co-catalyst incombination with the high-silica aluminosilicate catalyst led to asignificant increase in POS with increasing ethanol feed content.Indeed, at ethanol levels about 10 wt % or more in the feed, the productstream yielded a POS above about 80 wt %. Comparing this with theresults shown in Table 1 with basic metal oxide co-catalyst included,the high-silica aluminosilicate catalyst showed at least about a 3 wt %improvement in POS over the SAPO at about 10-20% ethanol in thefeedstock.

Table 2 also indicates that POR increased steadily with increasingethanol content in the feedstock, whether the metal oxide co-catalyst ispresent or not. In Example 2, even at moderate ethanol content in thefeedstock, the high-silica aluminosilicate catalyst system yielded muchhigher POR values, in contrast to the comparable SAPO catalyst system inExample 1. Furthermore, with the high-silica aluminosilicate catalyst,the presence of the basic metal oxide co-catalyst with mixed alcoholfeeds did not show the same slight POR debit as in the comparable SAPOcatalyst case from Example 1; instead, particularly at 20% ethanol inthe feedstock, the aluminosilicate-yttria combination showed a slightPOR advantage over the aluminosilicate catalyst alone. In many cases,although not in every case, it can be desirable to have a high POR, asethylene monomer can tend to have a higher market value than propylenemonomer.

Table 2 further indicates that there is almost no detectableacetaldehyde content in the aluminosilicate-yttria combination catalystsystem, regardless of the ethanol feed content, which indicates apreferential dehydration of ethanol to ethylene in thealuminosilicate-yttria combination catalyst system, as opposed to thedehydrogenation reaction present in other variations in Examples 1-2.Thus, the co-use of the metal oxide co-catalyst with the high-silicaaluminosilicate catalyst can significantly control formation ofimpurities such as acetaldehyde in the olefin product.

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to variations notnecessarily illustrated herein. For this reason, then, reference shouldbe made solely to the appended claims for purposes of determining thetrue scope of the present invention.

1. A process for converting an oxygenate feed to a light olefin productcomprising: a) providing the oxygenate feed comprising a majority ofmethanol and at least about 5 wt % ethanol; b) providing a catalystcomposition comprising an aluminosilicate catalyst and a basic metaloxide co-catalyst, wherein the aluminosilicate catalyst has an Si:Alratio of at least about 50:1 and wherein the basic metal oxideco-catalyst comprises a Group 2 metal oxide, a Group 3 metal oxide, aGroup 4 metal oxide, hydrotalcite, or a combination thereof; and c)contacting the oxygenate feed with the catalyst composition underconditions sufficient to convert at least a portion of the oxygenatefeed to a light olefin product.
 2. The process of claim 1, wherein theSi:Al ratio of the aluminosilicate catalyst is at least about 150:1. 3.The process of claim 1, wherein the aluminosilicate catalyst comprises amolecular sieve having a structure comprising CHA, AEI, an intergrowththereof, or a combination thereof.
 4. The process of claim 1, whereinthe aluminosilicate catalyst comprises zeolite beta, ZSM-5, ZSM-11,ZSM-12, ZSM-20, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-48, ZSM-50,ZSM-58, MCM-1, MCM-2, MCM-3, MCM-4, MCM-5, MCM-9, MCM-10, MCM-14,MCM-22, MCM-41, M-41S, MCM-48, MCM-49, MCM-56, ultrastable Y zeolite(USY), mordenite, SSZ-13, ECR-18, an intergrowth thereof, or acombination thereof.
 5. The process of claim 1, wherein the basic metaloxide co-catalyst absorbs more than 0.03 mg of CO₂ per square meter ofco-catalyst surface area at about 100° C.
 6. The process of claim 5,wherein the basic metal oxide co-catalyst absorbs more than 0.035 mg ofCO₂ per square meter of co-catalyst surface area at about 100° C.
 7. Theprocess of claim 1, wherein the basic metal oxide co-catalyst absorbsless than 5 mg of CO₂ per square meter of metal oxide surface area atabout 100° C.
 8. The process of claim 1, wherein the basic metal oxideco-catalyst comprises yttria.
 9. The process of claim 1, wherein theratio of aluminosilicate catalyst to basic metal oxide co-catalyst isfrom about 3:2 to about 15:1.
 10. The process of claim 1, wherein theoxygenate feed comprises at least about 60 wt % methanol and at leastabout 10 wt % ethanol.
 11. The process of claim 1, wherein the olefinproduct has (i) a prime olefin ratio of at least 1.5:1, (ii) a primeolefin selectivity of at least 80%, or (iii) both (i) and (ii).
 12. Theprocess of claim 11, wherein the olefin product has (i) a prime olefinratio of at least about 1.8:1, (ii) a prime olefin selectivity of atleast about 81%, or (iii) both (i) and (ii).
 13. The process of claim 1,wherein the olefin product has an aldehyde content of not more thanabout 5,000 wppm.
 14. The process of claim 13, wherein the olefinproduct has an aldehyde content of not more than about 1,500 wppm. 15.The process of claim 1, wherein the catalyst composition is contactedwith the oxygenate feed at a temperature from about 450° C. to about580° C.
 16. A process for converting an oxygenate feed to an olefinproduct comprising a) providing the oxygenate feed; b) providing acatalyst composition comprising an aluminosilicate catalyst and a basicmetal oxide co-catalyst, wherein the aluminosilicate catalyst has anSi:Al ratio of at least about 50:1 and wherein the basic metal oxideco-catalyst comprises a Group 2 metal oxide, a Group 3 metal oxide, aGroup 4 metal oxide, hydrotalcite, or a combination thereof; and c)contacting the oxygenate feed with the catalyst composition underconditions sufficient to convert at least a portion of the oxygenatefeed to a light olefin product having i) a prime olefin ratio of atleast 1.5:1, ii) a prime olefin selectivity of at least 80%, or iii)both (i) and (ii).
 17. The process of claim 16, wherein the oxygenatefeed comprises a majority of methanol and at least about 5 wt % ethanol.18. The process of claim 16, wherein the olefin product has an aldehydecontent of not more than about 5,000 wppm.
 19. The process of claim 16,wherein the basic metal oxide co-catalyst absorbs more than 0.03 mg ofCO₂ per square meter of co-catalyst surface area at about 100° C.
 20. Aprocess for converting an oxygenate feed to an olefin productcomprising: a) providing the oxygenate feed comprising a majority ofmethanol and at least about 5 wt % ethanol; b) providing a catalystcomposition comprising an aluminosilicate catalyst and a basic metaloxide co-catalyst, wherein the aluminosilicate catalyst has an Si:Alratio of at least about 50:1 and wherein the basic metal oxideco-catalyst comprises a Group 2 metal oxide, a Group 3 metal oxide, aGroup 4 metal oxide, hydrotalcite, or a combination thereof; and c)contacting the oxygenate feed with the catalyst composition underconditions sufficient to convert at least a portion of the oxygenatefeed to a light olefin product having an aldehyde content of not morethan about 3,000 wppm.
 21. The process of claim 20, wherein the olefinproduct has (i) a prime olefin ratio of at least 1.5:1, (ii) a primeolefin selectivity of at least 80%, or (iii) both (i) and (ii).
 22. Theprocess of claim 20, wherein catalyst composition further comprises abasic metal oxide co-catalyst that absorbs more than 0.03 mg of CO₂ persquare meter of co-catalyst surface area at about 100° C.